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Abstract:

There are provided a paper conveying apparatus, a jam detection method
and a computer-readable, non-transitory medium that can suppress
erroneous detection of a jam by sound due to the sound which a paper
which has a wrinkle generates. The paper conveying apparatus includes a
separator, a sound signal generator, provided with a sound detector
provided at a downstream side of the separator, for generating a sound
signal in accordance with the sound generated by a paper during
conveyance, a sound jam detector for determining whether a jam has
occurred based on the sound signal, and a wrinkle detector, provided at a
downstream side of the separator, for detecting optically a wrinkle of a
paper, wherein the sound jam detector changes the method of detection of
the jam when the wrinkle detector detects a wrinkle of a paper.

Claims:

1. A paper conveying apparatus comprising: a separator; a sound signal
generator, provided with a sound detector provided at a downstream side
of the separator in a paper conveyance direction, for generating a sound
signal corresponding to a sound generated by a paper during conveyance of
the paper; a sound jam detector for determining whether a jam has
occurred based on the sound signal; and a wrinkle detector, provided at a
downstream side of the separator in the paper conveyance direction, for
optically detecting a wrinkle of the paper, wherein the sound jam
detector changes the method of detection of the jam when the wrinkle
detector detects the wrinkle of the paper.

2. The paper conveying apparatus according to claim 1, wherein the
wrinkle detector is provided at an upstream side of the sound detector in
the paper conveyance direction.

3. The paper conveying apparatus according to claim 1, wherein the
wrinkle detector has an optical sensor, and the optical sensor optically
detects a wrinkle of a paper and reads an image from the paper.

4. The paper conveying apparatus according to claim 1, wherein the
wrinkle detector includes an equal magnification optical sensor.

5. The paper conveying apparatus according to claim 1, wherein the
wrinkle detector has an infrared light emitter for emitting infrared
light to a paper and an infrared light detector for optically detecting
infrared light reflected from the paper.

6. A jam detection method comprising: acquiring a sound signal from a
sound signal generator, provided with a sound detector provided at a
downstream side of the separator in a paper conveyance direction, for
generating the sound signal corresponding to a sound generated by a paper
during conveyance of the paper; determining whether a jam has occurred
based on the sound signal; detecting, by a computer, an output of a
wrinkle detector, provided at a downstream side of the separator in the
paper conveyance direction, for detecting optically a wrinkle of a paper;
and changing by the computer the method of detection of the jam when the
wrinkle of a paper is detected, in the determining step.

7. A computer-readable, non-transitory medium storing a computer program,
wherein the computer program causes a computer to execute a process, the
process comprising: acquiring a sound signal from a sound signal
generator, provided with a sound detector provided at a downstream side
of a separator in a paper conveyance direction, for generating the sound
signal corresponding to a sound generated by a paper during conveyance of
the paper; determining whether a jam has occurred based on the sound
signal; detecting an output of a wrinkle detector, provided at a
downstream side of the separator in the paper conveyance direction, for
detecting optically a wrinkle of a paper; and changing by the computer
the method of detection of the jam when the wrinkle of a paper is
detected, in the determining step.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priority
of prior Japanese Patent Application No. 2012-185247, filed on Aug. 24,
2012, the entire contents of which are incorporated herein by reference.

[0003] In a paper conveying apparatus of an image reading apparatus, image
copying apparatus, etc., sometimes a jam occurs when the paper moves
along the conveyance path. In general, a paper conveying apparatus is
provided with the function of determining whether a jam has occurred by a
paper being conveyed to a predetermined position inside the conveyance
path within a predetermined time from the start of conveyance of the
paper and of stopping the operation of the apparatus when a jam has
occurred.

[0004] On the other hand, if a jam occurs, a large sound is generated in
the conveyance path, so the paper conveying apparatus can determine
whether a jam has occurred based on the sound which is generated on the
conveyance path and thereby detect the occurrence of a jam without
waiting for the elapse of the predetermined time.

[0005] A jam detection apparatus of a copier which converts the sound
which is generated on the conveyance path to an electrical signal and
determines that a jam has occurred when the time when the signal is over
a reference level exceeds a reference value has been disclosed (see
Japanese Laid-open Patent Publication No. 57-169767).

[0006] Further, a document scanner which acquires an image of a document
in an input tray which holds the document and which optimizes the sound
jam detection parameter when a wrinkle is detected has been disclosed
(see U.S. Patent Publication No. 2012/0019841A).

SUMMARY

[0007] When a paper which has a wrinkle is conveyed, a large sound is
generated on the conveyance path, so sometimes it is erroneously
determined whether a jam has occurred. Such a wrinkle is sometimes caused
during conveyance of the paper.

[0008] Accordingly, it is an object of the present invention to provide a
paper conveying apparatus and a jam detection method that can suppress
erroneous detection of an occurrence of a jam by sound due to the sound
which a paper which has a wrinkle generates and a computer-readable,
non-transitory medium storing a computer program for causing a computer
to implement such a jam detection method.

[0009] According to an aspect of the apparatus, there is provided a paper
conveying apparatus. The paper conveying apparatus includes a separator,
a sound signal generator, provided with a sound detector provided at a
downstream side of the separator in a paper conveyance direction, for
generating a sound signal corresponding to a sound generated by a paper
during conveyance of the paper, a sound jam detector for determining
whether a jam has occurred based on the sound signal, and a wrinkle
detector, provided at a downstream side of the separator in the paper
conveyance direction, for optically detecting a wrinkle of the paper,
wherein the sound jam detector changes the method of detection of the jam
when the wrinkle detector detects the wrinkle of the paper.

[0010] According to an aspect of the method, there is provide a jam
detection method. The jam detection method includes acquiring a sound
signal from a sound signal generator, provided with a sound detector
provided at a downstream side of a separator in a paper conveyance
direction, for generating the sound signal corresponding to a sound
generated by a paper during conveyance of the paper, determining whether
a jam has occurred based on the sound signal, and detecting, by a
computer, an output of a wrinkle detector, provided at a downstream side
of the separator in the paper conveyance direction, for optically
detecting a wrinkle of the paper, and changing by the computer the method
of detection of the jam when the wrinkle of the paper is detected, in the
determining step.

[0011] According to an aspect of the computer-readable, non-transitory
medium storing a computer program, the computer program causes a computer
to execute a process, including acquiring a sound signal from a sound
signal generator, provided with a sound detector provided at a downstream
side of a separator in a paper conveyance direction, for generating the
sound signal corresponding to a sound generated by a paper during
conveyance of the paper, determining whether a jam has occurred based on
the sound signal, and detecting an output of a wrinkle detector, provided
at a downstream side of the separator in the paper conveyance direction,
for optically detecting a wrinkle of a paper, and changing by the
computer the method of detection of the jam when the wrinkle of the paper
is detected, in the determining step.

[0012] The object and advantages of the invention will be realized and
attained by means of the elements and combinations particularly pointed
out in the claims. It is to be understood that both the foregoing general
description and the following detailed description are exemplary and
explanatory and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a perspective view of a paper conveying apparatus 100
according to an embodiment.

[0014]FIG. 2 is a view for explaining an example of the conveyance route
at the inside of the paper conveying apparatus 100.

[0015]FIG. 3 is an example of a block diagram which shows the general
configuration of a paper conveying apparatus 100.

[0016]FIG. 4 is a flow chart which shows an example of operation of
overall processing of a paper conveying apparatus 100.

[0017]FIG. 5 is a flow chart which shows an example of an abnormality
detection of the paper conveyance.

[0018]FIG. 6 is a flow chart which shows an example of operation of a
sound jam detection processing.

[0019]FIG. 7A is a view for explaining processing for detection of an
occurrence of a jam.

[0020] FIG. 7B is a view for explaining processing for detection of an
occurrence of a jam.

[0021]FIG. 7c is a view for explaining processing for detection of an
occurrence of a jam.

[0022] FIG. 7D is a view for explaining processing for detection of an
occurrence of a jam.

[0023]FIG. 8A is a view for explaining processing for detection of an
occurrence of a jam.

[0024]FIG. 8B is a view for explaining processing for detection of an
occurrence of a jam.

[0025]FIG. 9 is a view for explaining an example of a wrinkle detector
113.

[0026]FIG. 10 is a flow chart which shows an example of operation of
wrinkle detection processing.

[0027] FIG. 11 is a view which shows an example of a binarized image of a
wrinkle detection-use image of a paper which has a wrinkle.

[0028]FIG. 12 is a flow chart which shows an example of operation of a
position jam detection processing.

[0029]FIG. 13 is a flow chart which shows an example of operation of
multifeed detection processing.

[0030]FIG. 14 is a view for explaining properties of an ultrasonic
signal.

[0031]FIG. 15 is a view for explaining an example of a conveyance route
at the inside of a paper conveying apparatus 200 according to another
embodiment.

[0032] FIG. 16 is a flow chart which shows an example of operation of
overall processing of a paper conveying apparatus 200.

[0033] FIG. 17 is a view for explaining an example of a conveyance route
at the inside of a paper conveying apparatus 300 according to still
another embodiment.

[0034]FIG. 18 is a view which shows an example of another schematic
configuration of a wrinkle detector.

DESCRIPTION OF EMBODIMENTS

[0035] Hereinafter, a paper conveying apparatus, jam detection method, and
computer program according to an embodiment, will be described with
reference to the drawings. However, note that the technical scope of the
invention is not limited to these embodiments and extends to the
inventions described in the claims and their equivalents.

[0036]FIG. 1 is an exemplary embodiment of a perspective view which shows
a paper conveying apparatus 100 which is configured as an image scanner,
according to an embodiment.

[0038] The upper housing 102 is arranged at a position which covers the
top surface of the paper conveying apparatus 100 and is engaged with the
lower housing 101 by hinges so as to be able to be opened and closed at
the time of a paper jam, at the time of cleaning of the inside of the
paper conveying apparatus 100, etc.

[0039] The paper tray 103 is engaged with the lower housing 101 in a
manner enabling a paper to be placed. The paper tray 103 is provided with
side guides 104a and 104b which can be moved in a direction perpendicular
to a conveyance direction of the paper, that is, to the left and right
directions from the conveyance direction of the paper. By positioning the
side guides 104a and 104b to match with the width of the paper, it is
possible to limit the width direction of the paper.

[0040] The ejection tray 105 is engaged with the lower housing 101 by
hinges so as to be able to pivot in the direction which is shown by an
arrow mark A1. In the opened state as shown in FIG. 1, the ejected paper
can be held.

[0041] The operation button 106 is arranged on the surface of the upper
housing 102. If pushed, it generates and outputs an operation detection
signal.

[0042]FIG. 2 is a view for explaining an example of the conveyance route
at the inside of the paper conveying apparatus 100.

[0043] The conveyance route at the inside of the paper conveying apparatus
100 has a first paper detector 110, a paper feed roller 111, a retard
roller 112, a wrinkle detector 113, a microphone 114, a second paper
detector 115, an ultrasonic transmitter 116a, an ultrasonic receiver
116b, a first conveyor roller 117, a first driven roller 118, a third
paper detector 119, a first image capture unit 120a, a second image
capture unit 120b, a second conveyor roller 121, a second driven roller
122, etc.

[0044] The top surface of the lower housing 101 forms the lower guide 107a
of the conveyance path of the paper, while the bottom surface of the
upper housing 102 forms the upper guide 107b of the conveyance path of
the paper. In FIG. 2, the arrow mark A2 shows the conveyance direction of
the paper. Below, "upstream" means upstream of the conveyance direction
A2 of the paper, while "downstream" means downstream of the conveyance
direction A2 of the paper.

[0045] The first paper detector 110 has a contact detection sensor which
is arranged at an upstream side of the paper feed roller 111 and the
retard roller 112 and detects if a paper is placed on the paper tray 103.
The first paper detector 110 generates and outputs a first paper
detection signal which changes in signal value between a state in which a
paper is placed on the paper tray 103 and a state in which one is not
placed.

[0046] The microphone 114 is an example of a sound detector, detects the
sound generated by a paper during conveyance of the paper, and generates
and outputs an analog signal corresponding to the detected sound. The
microphone 114 is arranged at the downstream side of the paper feed
roller 111 and the retard roller 112 while fastened to the frame 108 at
the inside of the upper housing 102. A hole 107 is provided in the upper
guide 107b facing the microphone 114, so that the sound generated by the
paper during conveyance of the paper can be more accurately detected by
the microphone 114.

[0047] The second paper detector 115 has a contact detection sensor which
is arranged at a downstream side of the paper feed roller 111 and the
retard roller 112 and at an upstream side of the first conveyor roller
117 and first driven roller 118 and detects if there is a paper present
at that position. The second paper detector 115 generates and outputs a
second paper detection signal which changes in signal value between a
state at which there is a paper at that position and a state where there
is no paper there.

[0048] The ultrasonic transmitter 116a and the ultrasonic receiver 116b
are arranged near the conveyance path of the paper so as to face each
other across the conveyance path. The ultrasonic transmitter 116a
transmits an ultrasonic wave. On the other hand, the ultrasonic receiver
116b detects an ultrasonic wave which is transmitted by the ultrasonic
transmitter 116a and passes through the paper or papers, and generates
and outputs an ultrasonic signal comprised of an electrical signal
corresponding to the detected ultrasonic wave. Below, the ultrasonic
transmitter 116a and the ultrasonic receiver 116b will sometimes be
referred to altogether as the "ultrasonic sensor 116".

[0049] The third paper detector 119 has a contact detection sensor which
is arranged at a downstream side of the first conveyor roller 117 and the
first driven roller 118 and an upstream side of the first image capture
unit 120a and the second image capture unit 120b and detects if there is
a paper at that position. The third paper detector 119 generates and
outputs a third paper detection signal which changes in signal value
between a state where there is a paper at that position and a state where
there is no such paper there.

[0050] The first image capture unit 120a has a CIS (contact image sensor)
of an equal magnification optical system type which is provided with an
image capture element using CMOS's (complementary metal oxide
semiconductors) which are arranged in a line in the main scan direction.
This CIS reads the back surface of the paper and generates and outputs an
analog image signal. Similarly, the second image capture unit 120b has a
CIS of an equal magnification optical system type which is provided with
an image capture element using CMOS's which are arranged in a line in the
main scan direction. This CIS reads the front surface of the paper and
generates and outputs an analog image signal. Note that, it is also
possible to arrange only one of the first image capture unit 120a and the
second image capture unit 120b and read only one surface of the paper.
Further, instead of a CIS, it is also possible to utilize an image
capturing sensor of a reduced magnification optical system type using
CCD's (charge coupled devices). Below, the first image capture unit 120a
and the second image capture unit 120b will sometimes be referred to
overall as the "image capture units 120".

[0051] A paper which is placed on the paper tray 103 is conveyed between
the lower guide 107a and the upper guide 107b toward the paper conveyance
direction A2 by rotation of the paper feed roller 111 in the direction of
the arrow mark A3 of FIG. 2. The retard roller 112 rotates in the
direction of the arrow mark A4 of FIG. 2 at the time of paper conveyance.
Due to the action of the paper feed roller 111 and the retard roller 112,
when the paper tray 103 has a plurality of papers placed on it, among the
papers which are placed on the paper tray 103, only the paper which is in
contact with the paper feed roller 111 is separated. The conveyance of
papers other than the separated paper is restricted (prevention of
multifeed). The paper feed roller 111 and the retard roller 112 function
as a paper separator.

[0052] A paper is fed between the first conveyor roller 117 and the first
driven roller 118 while being guided by the lower guide 107a and the
upper guide 107b. The paper is sent between the first image capture unit
120a and the second image capture unit 120b by the first conveyor roller
117 rotating in the direction of the arrow mark A5 of FIG. 2. The paper
which is read by the image capture unit 120 is ejected onto the ejection
tray 105 by the second conveyor roller 121 rotating in the direction of
the arrow mark A6 of the FIG. 2.

[0053]FIG. 3 is an example of a block diagram which shows the general
configuration of a paper conveying apparatus 100.

[0055] The first image A/D conversion unit 140a converts an analog image
signal which is output from the first image capture unit 120a from an
analog to digital format to generate digital image data which it then
outputs to the central processing unit 150. Similarly, the second image
A/D conversion unit 140b converts the analog image signal which is output
from the second image capture unit 120b from an analog to digital format
to generate digital image data which it then outputs to the central
processing unit 150. Below, these digital image data will be referred to
as the "read image".

[0056] The sound signal generator 141 includes a microphone 114, a filter
142, an amplifier 143, a sound A/D conversion unit 144, etc., and
generates a sound signal. The filter 142 applies a bandpass filter which
passes a predetermined frequency band of a signal to an analog signal
which is output from the microphone 114 and outputs it to the amplifier
143. The amplifier 143 amplifies the signal which is output from the
filter 142 and outputs it to the sound A/D conversion unit 144. The sound
A/D conversion unit 144 converts the analog signal which is output from
the amplifier 143 to a digital signal and outputs it to the central
processing unit 150. Below, a signal which is output by the sound signal
generator 141 will be referred to as a "sound signal".

[0057] Note that, the sound signal generator 141 is not limited to this.
The sound signal generator 141 may include only the microphone 114, while
the filter 142, the amplifier 143, and the sound A/D conversion unit 144
may be provided outside of the sound signal generator 141. Further, the
sound signal generator 141 may include only the microphone 114 and the
filter 142 or only the microphone 114, the filter 142, and the amplifier
143.

[0058] The drive unit 145 includes one or more motors and uses control
signals from the central processing unit 150 to rotate the paper feed
roller 111, the retard roller 112, the first conveyor roller 117, and the
second conveyor roller 121 and operate to convey a paper.

[0059] The interface 146 has, for example, a USB or other serial bus-based
interface circuit and electrically connects with a not shown information
processing apparatus (for example, personal computer, portable data
terminal, etc.) to send and receive a read image and various types of
information. Further, it is also possible to connect a flash memory etc.,
to the interface 146 so as to store the read image.

[0060] The storage unit 147 has a RAM (random access memory), ROM (read
only memory), or other memory device, a hard disk or other fixed disk
device, or flexible disk, optical disk, or other portable storage device.
Further, the storage unit 147 stores a computer program, database,
tables, etc., which are used in various processing of the paper conveying
apparatus 100. The computer program may be installed on the storage unit
147 from a computer-readable, non-transitory medium such as a compact
disk read only memory (CD-ROM), a digital versatile disk read only memory
(DVD-ROM), or the like by using a well-known setup program or the like.
Furthermore, the storage unit 147 stores the read image.

[0061] The central processing unit 150 is provided with a CPU (central
processing unit) and operates based on a program which is stored in
advance in the storage unit 147. Note that, the central processing unit
150 may also be comprised of a DSP (digital signal processor), LSI (large
scale integrated circuit), ASIC (application specific integrated
circuit), FPGA (field-programming gate array), etc.

[0063] The central processing unit 150 control a drive operation of the
drive unit 145, control a paper read operation of the image capture unit
120, etc., to acquire a read image. Further, the central processing unit
150 has a control module 151, an image generator 152, a sound jam
detector 153, a position jam detector 154, a multifeed detector 155, a
wrinkle determination module 156, etc. These units are functional modules
which are realized by software which operate on a processor. Note that,
these units may be comprised of respectively independent integrated
circuits, a microprocessor, firmware, etc.

[0064]FIG. 4 is a flow chart which shows an example of operation of
overall processing of the paper conveying apparatus 100.

[0065] Below, referring to the flow chart which is shown in FIG. 4, an
example of the operation of the overall processing of the paper conveying
apparatus 100 will be explained. Note that, the flow of the operation
which is explained below is performed based on a program which is stored
in advance in the storage unit 147 mainly by the central processing unit
150 in cooperation with the elements of the paper conveying apparatus
100.

[0066] First, the central processing unit 150 stands by until a user
pushes the operation button 106 and an operation detection signal is
received from the operation button 106 (step S101).

[0067] Next, the central processing unit 150 determines whether the paper
tray 103 has a paper placed on it based on the first paper detection
signal which was received from the first paper detector 110 (step S102).

[0068] If the paper tray 103 does not have a paper placed on it, the
central processing unit 150 returns the processing to step S101 and
stands by until newly receiving an operation detection signal from the
operation button 106.

[0069] On the other hand, when the paper tray 103 has a paper placed on
it, the central processing unit 150 drives the drive unit 145 to rotate
the paper feed roller 111, retard roller 112, first conveyor roller 117,
and second conveyor roller 121 and convey the paper (step S103).

[0070] Next, the control module 151 determines whether an abnormality flag
is ON or not (step S104). This abnormality flag is set OFF at the time of
startup of the paper conveying apparatus 100 and is set ON if a later
explained abnormality detection processing determines that an abnormality
has occurred.

[0071] When the abnormality flag is ON, the control module 151, as an
abnormal processing, stops the drive unit 145 to stop the conveyance of
the paper, uses a not shown speaker, LED (light emitting diode), etc. to
notify the user of the occurrence of an abnormality, sets the abnormality
flag OFF (step S105), and ends the series of steps.

[0072] On the other hand, when the abnormality flag is not ON, the image
generator 152 makes the first image capture unit 120a and the second
image capture unit 120b read the conveyed paper and acquires the read
image through the first image A/D conversion unit 140a and the second
image A/D conversion unit 140b (step S106).

[0073] Next, the central processing unit 150 transmits the acquired read
image through the interface 146 to a not shown information processing
apparatus (step S107). Note that, when not connected to an information
processing apparatus, the central processing unit 150 stores the acquired
read image in the storage unit 147.

[0074] Next, the central processing unit 150 determines whether the paper
tray 103 has a paper remaining thereon based on the first paper detection
signal which was received from the first paper detector 110 (step S108).

[0075] When the paper tray 103 has a paper remaining thereon, the central
processing unit 150 returns the processing to step S103 and repeats the
processing of steps S103 to S108. On the other hand, when the paper tray
103 does not have any paper remaining thereon, the central processing
unit 150 ends the series of processing.

[0076]FIG. 5 is a flow chart which shows an example of an abnormality
detection of the paper conveyance of the paper conveying apparatus 100.

[0077] The flow of operation which is explained below is executed based on
a program which is stored in advance in the storage unit 147 mainly by
the central processing unit 150 in cooperation with the elements of the
paper conveying apparatus 100.

[0078] First, the sound jam detector 153 executes sound jam detection
processing (step S201). In the sound jam detection processing, the sound
jam detector 153 determines whether a jam has occurred based on the sound
signal which was acquired from the sound signal generator 141. Below,
sometimes a jam which is determined to exist by the sound jam detector
153 based on a sound signal will be called a "sound jam". Details of the
sound jam detection processing will be explained later.

[0079] Next, the position jam detector 154 performs position jam detection
processing (step S202). In the position jam detection processing, the
position jam detector 154 determines the occurrence of a jam based on the
second paper detection signal which is acquired from the second paper
detector 115 and the third paper detection signal which is acquired from
the third paper detector 119. Below, sometimes a jam which is determined
to exist by the position jam detector 154 based on the second paper
detection signal and third paper detection signal will be called a
"position jam". Details of the position jam detection processing will be
explained later.

[0080] Next, the multifeed detector 155 performs multifeed detection
processing (step S203). In the multifeed detection processing, the
multifeed detector 155 determines the occurrence of a multifeed of papers
based on the ultrasonic signal which was acquired from the ultrasonic
sensor 116. Details of the multifeed detection processing will be
explained later.

[0081] Next, the control module 151 determines whether an abnormality has
occurred in the paper conveyance processing (step S204). The control
module 151 determines that an abnormality has occurred if at least one of
a sound jam, position jam, and paper multifeed has occurred. That is, it
is determined that no abnormality has occurred when none of a sound jam,
position jam, or paper multifeed has occurred.

[0082] The control module 151 sets the abnormality flag to ON (step S205)
and ends the series of steps when an abnormality occurs in the paper
conveyance processing. On the other hand, when no abnormality occurs in
the paper conveyance processing, it ends the series of steps without
particularly performing any further processing. Note that, the flow chart
which is shown in FIG. 5 is repeatedly executed every predetermined time
interval.

[0083]FIG. 6 is a flow chart which shows an example of operation of a
sound jam detection processing.

[0084] The flow of operation which is shown in FIG. 6 is executed at step
S201 of the flow chart which is shown in FIG. 5.

[0086]FIG. 7A is a graph which shows an example of a sound signal. The
graph 700 which is shown in FIG. 7A shows a sound signal which is
acquired from the sound signal generator 141. The abscissa of graph 700
shows the time, while the ordinate shows the signal value of the sound
signal.

[0087] Next, the sound jam detector 153 generates a signal of the absolute
value of the sound signal received from the sound signal generator 141
(step S302).

[0088] FIG. 7B is a graph which shows an example of the signal of the
absolute value of the sound signal. The graph 710 which is shown in FIG.
7B shows the signal of the absolute value of the sound signal of the
graph 700. The abscissa of graph 710 shows the time, while the ordinate
shows the signal of the absolute value of the sound signal.

[0089] Next, the sound jam detector 153 extracts a shape of a signal of
the absolute value of the sound signal (step S303). The sound jam
detector 153 extracts the envelope as the shape of the signal of the
absolute value of the sound signal.

[0090]FIG. 7c is a graph which shows an example of the shape of a signal
of the absolute value of the sound signal. The graph 720 which is shown
in FIG. 7c shows the envelope 721 of the signal of the absolute value of
the sound signal of the graph 710. The abscissa of the graph 720 shows
the time, while the ordinate shows the absolute value of the signal value
of the sound signal.

[0091] Next, the sound jam detector 153 calculates a counter value which
it increases when the shape of the signal of the absolute value of the
sound signal is a first threshold value Th1 or more and which it
decreases when it is less than the first threshold value Th1 (step S304).
The sound jam detector 153 determines whether the value of the envelope
721 is the first threshold value Th1 or more at each predetermined time
interval (for example, sampling intervals of sound signal), increments
the counter value when the value of the envelope 721 is the first
threshold value Th1 or more, and decrements the counter value when it is
less than the first threshold value Th1.

[0092] FIG. 7D is a graph which shows an example of the counter value
which is calculated for the shape of the signal of the absolute value of
the sound signal. The graph 730 which is shown in FIG. 7D expresses the
counter value which is calculated for the envelope 721 of the graph 720.
The abscissa of the graph 720 shows the time, while the ordinate shows
the counter value.

[0093] Next, the sound jam detector 153 determines whether the counter
value is a second threshold value Th2 or more (step S305). The sound jam
detector 153 determines that a sound jam has occurred if the counter
value is the second threshold value Th2 or more (step S306), determines
that a sound jam has not occurred if the counter value is less than the
second threshold value Th2 (step S307), and then ends the series of
steps.

[0094] In FIG. 7c, the envelope 721 is the first threshold value Th1 or
more at the time T1 and thereafter does not become less than the first
threshold value Th1. For this reason, as shown in FIG. 7D, the counter
value increases from the time T1 and becomes the second threshold value
Th2 or more at the time T2, then the sound jam detector 153 determines
that a sound jam has occurred.

[0095] Note that, at step S303, instead of acquiring the envelope as the
shape of the signal of the absolute value of the sound signal, the sound
jam detector 153 may acquire a signal of the peak hold for the signal of
the absolute value of the sound signal (below, referred to as the "peak
hold signal"). For example, the central processing unit 150 holds the
local maximum value of the signal of the absolute value of the sound
signal for exactly a predetermined hold period and then attenuates it by
a constant attenuation rate to acquire the peak hold signal.

[0096]FIG. 8A and FIG. 8B are views for explaining the processing for
acquiring the peak hold signal from the sound signal and determining
whether a sound jam has occurred.

[0097] The graph 800 which is shown in FIG. 8A expresses the peak hold
signal 801 for the signal of the absolute value of the sound signal of
the graph 710. The abscissa of the graph 800 shows the time, while the
ordinate shows the absolute value of the signal value of the sound
signal.

[0098] The graph 810 which is shown in FIG. 8B shows the counter value
which was calculated for the peak hold signal 801 of the graph 800. The
abscissa of the graph 810 shows the time, while the ordinate shows the
counter value. The peak hold signal 801 becomes the first threshold value
Th1 or more at the time T3, becomes less than the first threshold value
Th1 at the time T4, again becomes the first threshold value Th1 or more
at the time T5, and does not become less than the first threshold value
Th1 after that. For this reason, as shown in FIG. 8B, the counter value
increases from the time T3, decreases from the time T4, again increases
from the time T5, and becomes the second threshold value Th2 or more at
the time T6, so it is determined that a sound jam has occurred.

[0099]FIG. 9 is a view for explaining an example of a wrinkle detector
113.

[0101] The light source 123 includes RGB color LEDs (light emitting
diodes) and a light guiding member and emits light to the surface of the
paper which is conveyed to the wrinkle detector 113. Note that, the light
source 123 emits light from a slanted direction with respect to the paper
conveyance direction A2.

[0102] The lens 124 makes the light which is reflected at the paper enter
the optical sensor 125. The lens 124 is, for example, comprised of a rod
lens array. By passage of the light of the light source 123 which was
reflected at the surface of the paper, an erect image of the surface of a
paper is displayed by equal magnification on a not shown line sensor of
the optical sensor 125.

[0103] The optical sensor 125 is a CIS of an equal magnification optical
type which is provided with an image capture element using CMOS's
arranged in a line in the main scan direction. It generates and outputs
an analog image signal in accordance with the light which passes through
the lens 124. The analog image signal which is output from the optical
sensor 125 is converted from an analog to digital format by the third
image A/D conversion unit 140c to acquire a digital image data which is
then output to the central processing unit 150. Below, this digital image
data will be referred to as a "wrinkle detection-use image".

[0104] Note that, the wrinkle detector 113 may have an optical sensor
using CCDs instead of a CIS. However, an equal magnification optical
sensor such as a CIS, compared with a reduced magnification optical
sensor using CCDs, has a shallower depth of object field. Differences in
brightness due to surface relief of the surface of the paper easily occur
at the image acquired by reading a paper. For this reason, for the
wrinkle detector 113, preferably an equal magnification optical sensor is
utilized. Note that, the wrinkle determination module 156 may also be
used for the sound jam detector 153.

[0105]FIG. 10 is a flow chart which shows an example of operation of
wrinkle determination processing.

[0106] The flow of operation which is explained below is performed based
on a program which is stored in advance in the storage unit 147 by mainly
a central processing unit 150 in cooperation with the elements of the
paper conveying apparatus 100.

[0109] Next, the wrinkle determination module 156 determines whether the
ratio of pixels which show one value in all pixels in the binarized image
of the wrinkle detection-use image is within a predetermined range (for
example, 40% to 60%) (step S403).

[0110] The wrinkle determination module 156 determines that a paper has a
wrinkle when the ratio of pixels which show one value in all pixels in
the binarized image of the wrinkle detection-use image is within a
predetermined range (step S404).

[0111] FIG. 11 shows an example of a binarized image 1100 of the wrinkle
detection-use image for a paper which has a wrinkle.

[0112] The binarized image 1100 which is shown in FIG. 11 is an image
acquired by binarizing the wrinkle detection-use image for a paper P
which has a wrinkle which is shown in FIG. 9. As shown in FIG. 9, when a
paper P which has a wrinkle is conveyed to the wrinkle detector 113, the
amount of light which is received by the optical sensor 125 differs
between a surface P1 which is directly struck by light from the light
source 123 and a surface P2 which light from the light source 123 does
not easily strike. For this reason, in a wrinkle detection-use image
which is generated from a paper P which has a wrinkle, differences in
brightness occur due to the wrinkle. At that binarized image 1100, there
is a tendency for just pixels expressing one of the values to not become
much greater. On the other hand, in most papers on which text, graphics,
etc. are printed, the region which expresses the background accounts for
the majority of the area, so if the paper does not have a wrinkle, in the
binarized image, there is a tendency for just pixels expressing one value
to become much greater.

[0113] If the wrinkle determination module 156 determines that a paper has
a wrinkle, the method of detection of a sound jam is changed (step S405)
and the series of steps is ended. For example, the wrinkle determination
module 156 increases the first threshold value Th1 for comparison with
the envelope or the peak hold signal for the sound jam detector 153 to
determine to increment or decrement the counter value. Note that, the
wrinkle determination module 156 may also increase the second threshold
value Th2 for comparison with the counter value for the sound jam
detector 153 to determine whether a jam has occurred. Further, when the
sound jam detector 153 acquires the peak hold signal and determines a
jam, the wrinkle determination module 156 may shorten the hold period
where the local maximum value is held or may increase the attenuation
rate. Due to this, even when conveyance of a paper which has a wrinkle
causes a large sound to be generated in the conveyance path, the sound
jam detector 153 does not easily determine the occurrence of a jam in the
sound jam detection processing and can be kept from erroneously
determining the occurrence of a jam.

[0114] On the other hand, at step S403, if the ratio of pixels which show
one value is not in a predetermined range, the wrinkle determination
module 156 determines the paper has no wrinkles (step S406). In this
case, the wrinkle determination module 156 ends the series of steps
without particularly performing any processing. Note that, the flow chart
which is shown in FIG. 10 is executed at the timing when the central
processing unit 150 drives the drive unit 145 to rotate the paper feed
roller 111 and the retard roller 112 and the front end of the paper
reaches the wrinkle detector 113.

[0115] Note that, at step S403, the wrinkle determination module 156 may
generate a histogram of the luminance values of the pixels of the wrinkle
detection-use image, determines that there is a wrinkle at the paper when
the number of luminance values with a distribution value (population) of
a predetermined value or more is a predetermined number or more, and
determines that there is no wrinkle at the paper when it is less than the
predetermined number. If the paper has a wrinkle, the wrinkle
detection-use image will have bright and dark parts due to the wrinkle
and will have pixels with various luminance values, so it is possible to
determine there is a wrinkle in a paper precisely by this as well.

[0116] As shown in FIG. 2, the wrinkle detector 113 is arranged at the
downstream side of the paper feed roller 111 and the retard roller 112,
that is, inside the paper conveying apparatus 100, so it is possible to
generate an image free of the effects of the lighting, natural light,
etc., illuminating the location at which the paper conveying apparatus
100 is installed. Further, the wrinkle detector 113 can detect a wrinkle
even when the initial paper has no wrinkle, but the paper feed roller 111
and the retard roller 112 cause a wrinkle in the paper.

[0117] Further, the microphone 114 is provided near the paper feed roller
111 and the retard roller 112 which separate the papers so as to detect
the sound which is generated at the paper feed roller 111 and retard
roller 112. On the other hand, as explained above, the wrinkle
determination module 156 determines whether a conveyed paper has a
wrinkle based on the image which the wrinkle detector 113 generates, and
changes the method of detection of a sound jam, using the result of
determination. For this reason, the wrinkle detector 113 is preferably
provided near the paper feed roller 111 and the retard roller 112 so that
it can output the image signal for the conveyed paper at as early a
timing as possible. In particular, the wrinkle detector 113 preferably
outputs an image signal for a conveyed paper before the microphone 114
outputs a sound signal for the conveyed paper, and preferably is provided
at the upstream side of the microphone 114.

[0118]FIG. 12 is a flow chart which shows an example of operation of a
position jam detection processing.

[0119] The flow of operation which is shown in FIG. 12 is executed at step
S202 of the flow chart which is shown in FIG. 5.

[0120] First, the position jam detector 154 stands by until the front end
of the paper is detected by the second paper detector 115 (step S501).
The position jam detector 154 determines that the front end of the paper
is detected at the position of the second paper detector 115, that is,
downstream of the paper feed roller 111 and retard roller 112 and
upstream of the first conveyor roller 117 and first driven roller 118,
when the value of the second paper detection signal from the second paper
detector 115 changes from a value which shows the state where there is no
paper to a value which shows the state where there is one.

[0121] Next, when the second paper detector 115 detects the front end of a
paper, the position jam detector 154 starts counting time (step S502).

[0122] Next, the position jam detector 154 determines whether the third
paper detector 119 has detected the front end of the paper (step S503).
The position jam detector 154 determines that the front end of the paper
is detected at the position of the third paper detector 119, that is,
downstream of the first conveyor roller 117 and first driven roller 118
and upstream of the image capture unit 120, when the value of the third
paper detection signal from the third paper detector 119 changes from a
value which shows the state where there is no paper to a value which
shows the state where there is one.

[0123] When the third paper detector 119 detects the front end of a paper,
the position jam detector 154 determines that no position jam has
occurred (step S504) and ends the series of steps.

[0124] On the other hand, if the third paper detector 119 detects the
front end of the paper, the position jam detector 154 determines whether
a predetermined time (for example, 1 second) has elapsed from the start
of counting time (step S505). If a predetermined time has not elapsed,
the position jam detector 154 returns to the processing of step S503 and
again determines whether the third paper detector 119 has detected the
front end of the paper. On the other hand, when a predetermined time has
elapsed, the position jam detector 154 determines that position jam has
occurred (step S506) and ends the series of steps. Note that, when
position jam detection processing is not required in the paper conveying
apparatus 100, this may be omitted.

[0125] Note that, when the central processing unit 150 detects that the
front end of a paper is downstream of the first conveyor roller 117 and
the first driven roller 118 by the third paper detection signal from the
third paper detector 119, it controls the drive unit 145 to stop the
rotation of the paper feed roller 111 and retard roller 112 so that the
next paper is not fed. After that, when the central processing unit 150
detects the rear end of the paper downstream of the paper feed roller 111
and the retard roller 112 by the second paper detection signal from the
second paper detector 115, it again controls the drive unit 145 to rotate
the paper feed roller 111 and retard roller 112 and convey the next
paper. Due to this, the central processing unit 150 prevents a plurality
of papers from being superposed in the conveyance path. For this reason,
the position jam detector 154 may start counting the time at the point of
time when the central processing unit 150 controls the drive unit 145 to
rotate the paper feed roller 111 and the retard roller 112 and determine
that a position jam has occurred when the third paper detector 119 does
not detect the front end of a paper within a predetermined time.

[0126]FIG. 13 is a flow chart which shows an example of operation of
multifeed detection processing.

[0127] The flow of operation which is shown in FIG. 13 is executed at step
S203 of the flow chart which is shown in FIG. 5.

[0129] Next, the multifeed detector 155 determines whether the signal
value of the acquired ultrasonic signal is less than the multifeed
detection threshold value (step S602).

[0130]FIG. 14 is a view for explaining properties of an ultrasonic
signal.

[0131] In the graph 1400 of FIG. 14, the solid line 1401 shows the
characteristic of the ultrasonic signal in the case where a single paper
is conveyed, while the broken line 1402 shows the characteristic of the
ultrasonic signal in the case where multifeed of papers has occurred. The
abscissa of the graph 1400 shows the time, while the ordinate shows the
signal value of the ultrasonic signal. Due to the occurrence of
multifeed, the signal value of the ultrasonic signal of the broken line
1402 falls in the section 1403. For this reason, it is possible to
determine whether multifeed of papers has occurred by whether the signal
value of the ultrasonic signal is less than the multifeed detection
threshold value ThA.

[0132] The multifeed detector 155 determines that multifeed of the papers
has occurred when the signal value of the ultrasonic signal is less than
the multifeed detection threshold value (step S603), determines that
multifeed of the papers has not occurred when the signal value of the
ultrasonic signal is the multifeed detection threshold value or more
(step S604), and ends the series of steps. Note that, when multifeed
detection processing is not necessary in the paper conveying apparatus,
this may be omitted.

[0133] As explained above in detail, the paper conveying apparatus 100 is
provided with a wrinkle detector 113 at the downstream side of the paper
feed roller 111 and the retard roller 112 and operates in accordance with
the flow chart which is shown in FIG. 4, FIG. 5, FIG. 6, and FIG. 10 so
as to be able to detect wrinkles which occur at the paper feed roller 111
and retard roller 112. Accordingly, even when wrinkles are caused after
conveyance, it becomes possible to suppress erroneous detection of the
occurrence of a jam by sound due to the sound which is generated by a
paper which has a wrinkle.

[0134] Further, the wrinkle detector 113 is provided at the downstream
side of the paper feed roller 111 and the retard roller 112 and is
arranged at the inside of the paper conveying apparatus 100. Therefore,
the wrinkle detection by the wrinkle detector 113 is not affected by the
lighting, natural light, etc., so it is possible to precisely determine
whether a conveyed paper has a wrinkle.

[0135]FIG. 15 is a view for explaining an example of a conveyance route
at the inside of a paper conveying apparatus 200 according to still
another embodiment.

[0136] The paper conveying apparatus 200 which is shown in FIG. 15
utilizes the first image capture unit 120a and the second image capture
unit 120b, instead of the wrinkle detector 113 of the paper conveying
apparatus 100 which is shown in FIG. 2, and shifts the position of the
microphone 114 to downstream of the first image capture unit 120a and the
second image capture unit 120b. This paper conveying apparatus 200
utilizes the read image based on the image signal which is output from
the image capture unit 120 as the wrinkle detection-use image. That is,
in this paper conveying apparatus 200, the image capture unit 120 reads
an image from a paper and functions as a wrinkle detector to optically
detect a wrinkle of the paper.

[0137] As explained above, the wrinkle detector is preferably provided at
the upstream side of the microphone, so the microphone 114 is arranged at
the downstream side of the image capture unit 120 while being fastened to
a frame 208 of the inside of the upper housing 102. Further, a position
of the upper guide 107b facing the microphone 114 is provided with a hole
209 for the microphone 114 to detect sound.

[0138] FIG. 16 is a flow chart which shows an example of operation of
overall processing of the paper conveying apparatus 200.

[0139] Below, while referring to the flow chart which is shown in FIG. 16,
an example of operation of the overall processing of the paper conveying
apparatus 200 will be explained. Note that, the flow of operation which
is explained below is performed based on a program which is stored in the
storage unit 147 in advance by mainly the central processing unit 150 in
cooperation with the elements of the paper conveying apparatus 200.

[0140] In the flow chart which is shown in FIG. 16, different from the
flow chart which is shown in FIG. 4, the paper conveying apparatus 200
utilizes the read image from the image capture unit 120 as a wrinkle
detection-use image, so performs paper reading processing before
determining whether the abnormality flag is ON. The processing of steps
S701 to S703, S705 to S706, and S708 which are shown in FIG. 16 is the
same as the processing of steps S101 to S103, S104 to S105, and S108
which are shown in FIG. 4, so explanation will be omitted. Below, only
the processing of steps S704 and S707 will be explained.

[0141] At step S704, the image generator 152 makes the first image capture
unit 120a and the second image capture unit 120b read the conveyed paper
and acquires the read image through the first image A/D conversion unit
140a and the second image A/D conversion unit 140b. The wrinkle
determination module 156 acquires the read image as the wrinkle
detection-use image which is used for wrinkle determination processing at
step S401 of the flow chart which is shown in FIG. 10.

[0142] Further, at step S706, if the control module 151 determines that
the abnormality flag is not ON, the central processing unit 150 transmits
the read image which is acquired at step S704 through the interface 146
to a not shown data processing apparatus (step S707).

[0143] As explained above in detail, even if the paper conveying apparatus
utilizes the image capture unit as a wrinkle detector and operates in
accordance with the flow chart which is shown in FIG. 16, it becomes
possible to precisely determine whether there is a wrinkle in a paper and
becomes possible to suppress erroneous detection of the occurrence of a
jam. Further, by using the optical sensor for reading a paper as the
optical sensor for wrinkle detection, reduction of the hardware costs
becomes possible.

[0144] FIG. 17 is a view for explaining an example of a conveyance route
at the inside of a paper conveying apparatus 300 according to still
another embodiment.

[0145] The paper conveying apparatus 300 which is shown in FIG. 17 is a
type of paper conveying apparatus with a conveyance path longer than the
paper conveying apparatus 100 which is shown in FIG. 2.

[0147] The wrinkle detector 305 is arranged at the downstream side of the
paper feed roller 303 and retard roller 304 and the upstream side of the
first microphone 306, second microphone 323, and third microphone 325.

[0148] The first microphone 306 detects the sound when papers are
separated by the paper feed roller 303 and retard roller 304. The second
microphone 323 detects the sound right before a paper is read by the
first image capture unit 324a and the second image capture unit 324b. The
third microphone 325 detects the conveyance sound of a paper at a part
where the conveyance path bends.

[0149] In the paper conveying apparatus 300, doubled papers which have
been picked up by the pick roller 302 from the paper loader 301 are
separated by the paper feed roller 303 and retard roller 304 and loaded
sheet by sheet to the conveyance path. A paper which is loaded into the
conveyance path is conveyed by the conveyor rollers and driven rollers,
is read by first image capture unit 324a and second image capture unit
324b, and is ejected to the paper ejector 326.

[0150] The central processing unit of the paper conveying apparatus 300
determines whether a jam has occurred at the positions at which the
microphones are arranged based on sound signals which the first
microphone 306, second microphone 323, and third microphone 325 generate.
The central processing unit determines whether there is wrinkle at the
paper from the wrinkle detection-use image based on the image signal of
the wrinkle detector 305 and, when judging there is a wrinkle, changes
the parameter for determining a jam based on the sound signals which the
first microphone 306, second microphone 323, and third microphone 325
generate.

[0151] Note that, the third microphone 325 is positioned at the downstream
side of the first image capture unit 324a and the second image capture
unit 324b. For this reason, the central processing unit may change the
parameter for determining a jam based on the sound signal which the third
microphone 325 generates, by using the result of determination whether
there is a wrinkle in a paper, using a read image based on the image
signals from the first image capture unit 324a and the second image
capture unit 324b. Due to this, the paper conveying apparatus 300 can
detect a wrinkle formed on a paper right before the paper is conveyed to
the first image capture unit 324a and second image capture unit 324b.

[0152] As explained above in detail, the paper conveying apparatus can
suppress erroneous detection of the occurrence of a jam even when there
are a plurality of microphones.

[0153]FIG. 18 is a view which shows an example of another schematic
configuration of a wrinkle detector.

[0154] The wrinkle detector 413 which is shown in FIG. 18 includes an
infrared light emitter 423 and an infrared light detector 424.

[0155] The infrared light emitter 423 emits infrared light (near infrared
light) on the surface of the paper which is conveyed to the wrinkle
detector 413. Note that, the infrared light emitter 423 emits light from
a slanted direction with respect to the paper conveyance direction A2.

[0156] The infrared light detector 424 optically detects infrared light
which is reflected from the paper and generates and outputs an analog
image signal corresponding to the infrared light which was received. In
this case, this analog image signal is converted from an analog to
digital format and the digital image data is utilized as a wrinkle
detection-use image.

[0157] Infrared light, which has a wavelength longer than visible light,
has the property of being resistant to the effects of the paper quality
(fiber structure of cellulose). Further, most dyes and materials absorb a
specific wavelength of visible light, but do not absorb infrared light.
For this reason, the paper conveying apparatus can use infrared light to
reduce the effects of the paper quality of the paper and the information
which is printed on the paper and thereby precisely determine for the
presence of a wrinkle.

[0158] As explained above in detail, the paper conveying apparatus can use
infrared light to more precisely detect the occurrence of a jam.

[0159] According to the paper conveying apparatus and the jam detection
method, and the computer-readable, non-transitory medium, the wrinkle
detector is provided at the downstream side of the separator in the paper
conveyance direction and can detect a wrinkle which has occurred at the
separator, so it is possible to suppress erroneous detection of the
occurrence of a jam by sound due to the sound which a paper which has a
wrinkle generates.

[0160] All examples and conditional language recited herein are intended
for pedagogical purposes to aid the reader in understanding the invention
and the concepts contributed by the inventor to furthering the art, and
are to be construed as being without limitation to such specifically
recited examples and conditions, nor does the organization of such
examples in the specification relate to a showing of the superiority and
inferiority of the invention. Although the embodiment(s) of the present
inventions have been described in detail, it should be understood that
the various changes, substitutions, and alterations could be made hereto
without departing from the spirit and scope of the invention.